intel_idle: Disable promotion to C1E on Jasper Lake and Elkhart Lake

[ Upstream commit 5bb33212b5c664396e5de4cd5a2999abb84a3978 ]

PCIe ethernet throughut is sub-optimal on Jasper Lake and Elkhart Lake.

The CPU can take long time to exit to C0 to handle IRQ and perform DMA
when C1E has been entered.

For this reason, adjust intel_idle to disable promotion to C1E and still
use C-states from ACPI _CST on those two platforms.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=219023
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Link: https://patch.msgid.link/20240820041128.102452-1-kai.heng.feng@canonical.com
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 88470602b789e11c486608cd9a64e415066338e4..67aebfe0fed66550540ed69b06bb38c5640f7227 100644 (file)
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -1530,6 +1530,10 @@ static const struct idle_cpu idle_cpu_dnv __initconst = {
        .use_acpi = true,
 };
 
+static const struct idle_cpu idle_cpu_tmt __initconst = {
+       .disable_promotion_to_c1e = true,
+};
+
 static const struct idle_cpu idle_cpu_snr __initconst = {
        .state_table = snr_cstates,
        .disable_promotion_to_c1e = true,
@@ -1594,6 +1598,8 @@ static const struct x86_cpu_id intel_idle_ids[] __initconst = {
        X86_MATCH_VFM(INTEL_ATOM_GOLDMONT,      &idle_cpu_bxt),
        X86_MATCH_VFM(INTEL_ATOM_GOLDMONT_PLUS, &idle_cpu_bxt),
        X86_MATCH_VFM(INTEL_ATOM_GOLDMONT_D,    &idle_cpu_dnv),
+       X86_MATCH_VFM(INTEL_ATOM_TREMONT,       &idle_cpu_tmt),
+       X86_MATCH_VFM(INTEL_ATOM_TREMONT_L,     &idle_cpu_tmt),
        X86_MATCH_VFM(INTEL_ATOM_TREMONT_D,     &idle_cpu_snr),
        X86_MATCH_VFM(INTEL_ATOM_CRESTMONT,     &idle_cpu_grr),
        X86_MATCH_VFM(INTEL_ATOM_CRESTMONT_X,   &idle_cpu_srf),
@@ -2142,7 +2148,7 @@ static void __init intel_idle_cpuidle_driver_init(struct cpuidle_driver *drv)
 
        drv->state_count = 1;
 
-       if (icpu)
+       if (icpu && icpu->state_table)
                intel_idle_init_cstates_icpu(drv);
        else
                intel_idle_init_cstates_acpi(drv);
@@ -2276,7 +2282,11 @@ static int __init intel_idle_init(void)
 
        icpu = (const struct idle_cpu *)id->driver_data;
        if (icpu) {
-               cpuidle_state_table = icpu->state_table;
+               if (icpu->state_table)
+                       cpuidle_state_table = icpu->state_table;
+               else if (!intel_idle_acpi_cst_extract())
+                       return -ENODEV;
+
                auto_demotion_disable_flags = icpu->auto_demotion_disable_flags;
                if (icpu->disable_promotion_to_c1e)
                        c1e_promotion = C1E_PROMOTION_DISABLE;